Composite Li-Ion Anodes from Recycled Silicon

W. XuElectrochemical Materials, US

Keywords: silicon, kerf, lithium ion, battery

Summary:

Silicon byproducts from sources such as kerf are difficult to use directly as lithium-ion batteries since key parameters such as silicon particle size, surface oxides, and impurities, do not fulfill the requirements for silicon anode materials. We have developed a method of integrating silicon into a Li-ion battery anode material using a highly scalable approach based on utilizing metallurgical grade recycled material. The process consists of reducing silicon powder to a desired size, subsequent modification of the particles surface and mixing of the resulting powder with a standard anode paste. Depending on the silicon concentration the resulting anode material has specific capacity ranging from 700 to 900 mAh·g-1 which is 2 to 3 times higher than compositions based on graphite only. The resulting anode from recycled silicon was assembled and evaluated in a lithium secondary coin cell with a lithium cobalt oxide cathode. The coin cell is demonstrated with a reversible capacity over 160 mAh·g-1 for over 500 cycles. The work, demonstrates silicon anodes can be prepared from recycled silicon. The process to recover silicon as anode material from waste shows great commercial potential for future silicon-based lithium rechargeable batteries.